An inspired performance from Fraser Forster earned Southampton a goalless draw against Arsenal on Tuesday night as the Gunners dropped to fourth in the Premier League.
Forster, who has not conceded since returning to the side against Watford, made two smart saves from Mesut Ozil in the first half, before making a series of stops from Ozil again, substitute Theo Walcott and Alexis Sanchez as Arsenal piled on the pressure after the break.
Laurent Koscielny headed over from close range, while Southampton's best opportunity fell to Sadio Mane, but the Saints forward could only scuff wide after latching onto Virgil van Dijk's flick.
Arsenal drop to fourth following victories for title rivals Leicester City, Tottenham and Manchester City, while the draw extends Southampton's unbeaten run to four matches.
Both sides were without their January signings as Arsene Wenger and Ronald Koeman each made two changes from their last league outings. Charlie Austin, ruled out with a slight knock, should return at the weekend for the Saints, while Mohamed Elneny was not included in the Arsenal squad after making his debut in the FA Cup.
In an even first half the Gunners carved out the better opportunities, with Forster twice denying Ozil from point-blank range.
The German international produced a sublime piece of skill to test the Southampton goalkeeper 11 minutes in, plucking a long ball out of the air with his first touch before turning it goalwards with his second, but Forster saved with an outstretched leg.
His stop 10 minutes later was the pick of the bunch, though, as he instinctively kept out Ozil's jabbed finish from three yards after Giroud's header put the Arsenal attacker in on goal.
Despite the opportunities for the home side it was not one-way traffic, and Southampton served warnings through Dusan Tadic and Mane.
The former twisted and turned on the edge of the box before firing tamely at Petr Cech, while Mane wasted the Saints' best chance of the half, latching onto a Van Dijk header only to miscue past the post.
The Gunners finished the half on top as Joel Campbell picked out Ozil six yards out on the stroke of half-time, but the Arsenal man was quickly crowded out by a Southampton defence looking to post its fourth consecutive shutout.
Wenger's side kept the pressure on, with Forster tipping over Olivier Giroud's curling effort four minutes after the restart, and looked set to take the lead through Walcott shortly after only for the Southampton 'keeper to again stand firm.
Southampton's goal continued to live a charmed life as Koscielny headed over the bar from four yards, and even when Forster was beaten, Wenger's side still failed to break the deadlock - James Ward-Prowse clearing off the line from Sanchez's low drive with 20 minutes to play.
Mane and Long had opportunities on the break, with the former drawing a routine save from Cech, but the Gunners were swiftly back on the front foot as they pushed for a winner.
Van Dijk denied Ozil with the Arsenal attacker poised to pull the trigger, while Forster's strong right hand denied Sanchez on the follow-up, but despite six minutes of added time, the Gunners could not find a breakthrough.
Arsenal's 10 shots on target without a goal is the joint most in a league game this season, and the Gunners are now winless in the Premier League since victory over Newcastle a month ago.
They face Bournemouth at the Vitality Stadium at the weekend, five points off top-of-the-table Leicester, while Southampton will look to keep their fifth straight clean sheet against West Ham on Saturday Night Football.
Arsenal: Cech (6), Bellerin (6), Gabriel (6), Koscielny (6), Monreal (6), Flamini (6), Ramsey (6), Campbell (5), Ozil (7), Sanchez (7), Giroud (6)
Subs used: Coquelin (5), Walcott (6)
Southampton: Forster (8), Soares (6), Fonte (7), Van Dijk (7), Bertrand (6), Ward-Prowse (6), Romeu (7), Wanyama (7), Tadic (6), Mane (6), Long (6)
Subs used: Pelle (5), Targett (6), Juanmi (6)
Man of the match: Fraser Forster